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Copyright>        Copyright (C) 1986-2023 Altair Engineering Inc.
Copyright>
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Copyright>
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Chd|====================================================================
Chd|  DT18LAW                       source/materials/time_step/dt18law.F
Chd|-- called by -----------
Chd|        DTMAIN                        source/materials/time_step/dtmain.F
Chd|-- calls ---------------
Chd|====================================================================
      SUBROUTINE DT18LAW(PM,IPM,MAT,EINT,THETA,DELTAX,DTX)
C
C     CALCUL DES DT ELEM LOI NO 18 THERMIQUE PURE
C
C-----------------------------------------------
C   I m p l i c i t   T y p e s
C-----------------------------------------------
#include      "implicit_f.inc"
C-----------------------------------------------
C   G l o b a l   P a r a m e t e r s
C-----------------------------------------------
#include      "mvsiz_p.inc"
C-----------------------------------------------
C   C o m m o n   B l o c k s
C-----------------------------------------------
#include      "vect01_c.inc"
#include      "param_c.inc"
C-----------------------------------------------
C   D u m m y   A r g u m e n t s
C-----------------------------------------------
      INTEGER IPM(NPROPMI,*),MAT(*)
C     REAL
      my_real
     .   PM(NPROPM,*), EINT(*), THETA(*), DELTAX(*), DTX(*)
C-----------------------------------------------
C   L o c a l   V a r i a b l e s
C-----------------------------------------------
      INTEGER I, ITFUN
C     REAL
      my_real
     .   A(MVSIZ), B(MVSIZ), SPH(MVSIZ), T0
C=======================================================================
      DO I=LFT,LLT
      SPH(I)=PM(69,MAT(I))
      A(I)  =PM(75,MAT(I))
      B(I)  =PM(76,MAT(I))
      END DO

      DO I=LFT,LLT
      THETA(I)=EINT(I)/SPH(I)
      END DO

      DO I=LFT,LLT
      T0=PM(79,MAT(I))
      ITFUN = IPM(11,MAT(I))
      IF(ITFUN/=0)THEN
       THETA(I) = T0 ! missing function value !
      ENDIF
      END DO

      DO I=LFT,LLT
      DTX(I)=HALF*DELTAX(I)**2*SPH(I)/(A(I)+B(I)*THETA(I))
      ENDDO
C-----------
      RETURN
      END
